var arr1 = [1,2,3,4];
var arr2 = [2,3,4,5,6,7,8,9];

async function fun(arr1, arr2) {
  const array = arr1.concat(arr2).filter(function(value) {
    // console.log(value);
  })
  console.log(array);
}

fun(arr1, arr2);